Lead acid, gel-cell and sealed lead acid batteries yield their optimum life-span when they maintain an appropriate and adequate charge and are not repeatedly, depleted and recharged. It is a well known phenomena that lead acid, gel-cell and sealed lead acid batteries lose their charge if not electrically engaged with a charging apparatus on a frequent and regular basis. Furthermore, when lead acid, gel-cell and sealed lead acid batteries sit idly, they will lose their charge due to natural discharging.
Batteries which are used less than once a month are prone to premature failure due to the natural discharging effect of the battery. Although lead acid, gel-cell and sealed lead acid batteries can be recharged, the cyclic charging and discharging will prematurely deteriorate these batteries. A 12 volt lead acid, gel-cell or sealed lead acid battery will yield a maximum life expectancy when the voltage is continuously kept at the manufacturer's recommended voltage of 13.8 volts.
When recharging current supplied to a rechargeable battery is continued past a point of full recharge, the battery may suffer the effects of overcharging, out-gassing, overheating, speeding up of the electrolyte reaction within the battery, evaporation of electrolyte and ultimately resulting in shortening the life of a 12 volt lead acid, gel-cell or sealed lead acid battery.
A large number of battery chargers have been developed for use in recharging batteries. Typically, battery charges have used the principal of current limiting to recharge batteries. However, using such chargers over an extended period of time, can overcharge the battery and result in premature failure. Some of these battery chargers also include sophisticated voltage monitors and charging controllers, however, these chargers similarly fail to protect against overcharging during unsupervised extended time use.
It is, therefore, a feature of the present invention to provide a current limited voltage regulated dual rate battery maintainer and charging apparatus which in normal use provides for charge preservation of 12 volt lead acid, gel-cell and sealed lead acid batteries at the manufacturer's suggested voltage.
Another feature of the present invention is to provide a current limited voltage regulated dual rate battery maintainer and charging apparatus which meets with 12 volt lead acid, gel-cell and sealed lead acid battery manufacturer's requirements for maintaining a 12 volt battery at it's optimum charge.
Another feature of the present invention is to provide a means which prevents harmful cyclic charging and discharging of 12 volt lead acid, gel-cell and sealed lead acid batteries.
Another feature of the present invention is to provide a means of continuous current limitation, to maintain the battery at a constant desirable voltage.
Another feature of the present invention is to provide safety features to protect from improper battery hookup, preventing the overcharging of an adequately charged or over-charged battery and preventing the charging of a battery with no potential for holding a charge.
U.S. Pat. No. 3,688,177 issued to Reeves et al. on Aug. 29, 1972 describes a battery charger which regulates the charging current by regulating the firing angle of a controllable rectifier; U.S. Pat. No. 3,919,618 which issued to Coleman, et al. on Nov. 11, 1975 describes a hysteresis battery charger and includes a charging network having a series of pass elements for delivering charging current to a battery; U.S. Pat. No. 4,386,308 which issued to Emile, Jr., et al. on May 31, 1983 teaches a hysteresis type battery charger including a circuit for monitoring battery voltage and controlling charging current to a battery; U.S. Pat. No. 4,509,102 which issued to Ayer on Apr. 2, 1985 describes a battery current switch having an opto-isolated switch; U.S. Pat. No. 4,663,580 which issued to Wortman on May 5, 1987 describes a sealed lead acid battery float charger and power supply which includes a predetermined non-linear temperature coefficient compensation network; U.S. Pat. No. 4,698,580 which issued to Yang on Oct. 6, 1987 describes an automatic charging or cut-off circuit device for intermittent pulsating DC charging power supply which automatically cuts-off when the battery becomes fully charged; U.S. Pat. No. 4,742,290 which issued to Sutphin et al. on May 3, 1988 teaches a recharging battery charger; and U.S. Pat. No. 5,013,992 which issued to Eavenson et al. on May 7, 1991 teaches a microprocessor controlled battery charger.
The aforementioned devices, although useful for a particular application, do not provide for the same purpose, needs or applications desired as those in the current device. Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will become apparent from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized by means of the combinations and steps particularly pointed out in the appended claims.